Method for making turbine rotors



Mar. 6, 1923.

A. w. CARLSON. METHOD FOR MAKING TU RB INE ROTORS.

FILED FEB. 23. I9l8.

fa CLERK/I (3 CI CI G (17c! z 2b fz zvzzzgazz a Patented Mar. 6 1923.

D "sem AXEL W. CARLSON', OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO CA RLING TURBINEWBLOWER 00., 0F V70RCESTER,.MASSACHU'SETTS, A CORPORATION OF MASSACHUSETTS.

METHOD FOR MAKING-TURBINE ROTOR$.

Application med February 23, 1918; serial'no. 218,860.

Another object is to provide anefiicient,

economical method of supporting the series of vanes and band 'in properly assembled circular shape, .and' for maintaining the same in such relatively fixed relation as a unitary element conditioned for handling, temporary storage or transportation, preparatory to their subsequent convenient placement for'facilitatingthe wheel casting operations; said vanes being primarily assembled inv circular form, concentrically clamped, and'externally surrounded and embedded in a complete annulus of core-mate rial applied and formed thereon as more:

fully hereinafter set forth.

It will be understood that I do not claim the] idea of attachingvanes or buckets of turbine rotors by casting or cast 'joints, nor broadly, the employment of a metal band having holes therethrough for" receiving and spacingv the shanks of the vanes; but my invention relates to the peculiar method illustrated in the drawings and specifically set forth in thefollowing description; the particular subject matter claimed being. definitelyexpressed in the summary. v

'In the accompanying drawings, F 1g. 1 represents a cross section, of a turbine rotor;

the righthand half of the view showing it.

clamp formed of equal" diameter to the in the casting mold. Fig. 2 represents a plan view, the quarters, taken at different,

levels; the upper portion" showing the rotor as completed; theright hand portion showing the structurev of the lower cla'mp plate and a section of the core-box at line X on Fig. 3; the left hand portion showing-the,

box and clamp plates; Oneside showing the.

core as formed therein, and the other side' showing the core-forming space with the rotor vanessupported therein ready for receiving the core material. Fig. 4: represents an "end and frontof one ofthe buckets or vanes, drawnto large scale. Fig. 5' rep resents a side and cross section of a portion of'the' perforated circular band for'spacing the vanes and forming the face of the rotor wheel, and Fig. 6 representsaside and cross section of a portion of the hoop forbracing the outer ends of the radial vanes;

Referring to the drawings, numeral 1" denotes the body disk or wheel'ofia turbine rotor; and 2 indicates the buckets or vanes radially disposed about the'periphery of the wheel for receiving the impinging forceof the impelling fluid. Said vanes are'm'ade of suitable composition metal, such as heretofore employed in turbine buckets; and are i I individually formed substantially as shown inv Fig.4, each having at its inner end transverse offsets or shoulders'a, and alongitu dinally projecting reduced shank 5, preferably proportioned approximately as indi{ cated, and provided with notches or grooves across the sides. At their outer end the vanes are best formed with endwise projecting lugs 6 at the respective corners, with an intervening fiat end surface. In my method of manufacture the entire series of vanes are'fixedly enveloped, in the peculiar manner specified, within a com plete annulus of core material. For this purpose I preferably employ the'means.

illustrated in Fig. 3," but claimed in a sep-, arate application. ln said means the numera'l 10 indicates an'annular core box, and 12 a circular clamp-plate adapted to be con centrically supported within the box'lO byan offset or shoulder 11, or by other 'efiicient means. 13 indicates the upper plate of the plate 12, andsuperposedthereon with .ltS underv surface counter-matching the upper surface of the'lower plate; their peripheral edges being approximately upright, or

slightly inclined from'their junction line outward. The adjacent faces "of the clampplates 12 and 13 are adapted for receiving 16 arranged therein whereby the clamp can be conveniently tightened and released, as desired. The combined core-box and clamping devices, as a means, is made the subject of a divisional application, Serial No. 229,729; filed April 20, 1918.

The diameter of the clamp-plates 12 and 13 is made the same as the required diameter for the rotor wheel casting, while the thickness of said plates together is such as to give the required depth of core.

I The circular band of metal 20, is preferably a thin strip or ribbon of copper or steel about one-sixteenth inch, more or less, in thickness. and of a width equal to or slightly greater than the rim 7 of the wheel 1. Said band is provided along its medial line with, a series of perforations or holes 21 formed therethrough, of a shape corresponding with the cross section shape of the shanks 5 of the vanes, and spaced to correspond with the desired series spacing of the vanes about the circumference of the rotor. The diameter of the circular band 2 0 is such as will fit closely, but removably, about the peripheral faces of the adjacent clamp plates 12 and 13, with its openings 21 coincident with the clamp-spaces 15,.

According to my improved method the band 20 is primarily disposed about the periphery of the circular clamp-plates and thereby supported in accurate circular form; said band being arranged around the clampplates when the latter are slightly separated, sufiieient for insertion of the shanks 5 .upon

the inner ends of the vanes. The shanks of all the vanes are then inserted respectively.

through the openings 21 inthe band, into the space or spaces 15 between the clamp plates, as at 23, Fig. 2; the shoulder 4: restingagainst the exterior of the band, and the several vanes standing out radially at their respective spaced positions. The screws 16 are then turned down firmly clamping the shanks in position and retaining the vanes in their proper relation. The clamp-plates. are then placed withinthe circular-box 10, with the clamped vanes projecting outward within the annular space 2 1 between the edges of the clamp-plates and rim of the box 10 Said space is then filled with core material completely encasing the vanes2 and band 20 therein, and forming a complete annular core 25 in which the vanes and band are retained at their required posit-ion. The top of said core is leveled off with the cover 17, of the box. A metal ring or hoop 18 of round or flat wire may, when desired, be embedded in the material for reinforcing the core.

The clamp-plates 12 and 13, together with the formed core 25, are then removed from the box 10; the clamp screw 16 turnedout and the clamp-plates taken off, leaving the band 20 retained in the core with the shanks 5 of the vanes 2 cleanly protecting inward from the inner face of the band, as best shown at 5 on Fig. 2. This circular core is baked to give it proper consistency about the embedded vanes, and forms a complete cylindrical annulus.

A casting mold 26 of molding sand is formed in the flask-27, by the use of a suit ably shaped pattern in the usual manner of foundry practice. 'When the pattern is removed from the sand, the circular core con-- taining the band and the. series of vanes 2 is placed in the mold with the s anks projecting inward Within the ma rix, The molten metal, usual y a bronze compos tio is. then poured. into t e matr x in Well known manner and flows outward against the inner face of the band, embedding the inwardly projecting shanks f the vanes solidly and integrally within the metal of th circular im '7 of the WhQEa L. The cast metal, as it flows gainst he, hand 2Q, effects. n egral weld with the shanks 5f with the inner f ce f h band; since said hand sulfici'ently t in t avoid h i g as. he m lt n metal comes; in conta t. herewith; the exterior of the band being against the, core subi pr serves its or ginal s ape a surace.

As results of the m thod hcrei'nbefore described the manu acture of" turbi e rotors is facilitated. nd simplified, a d? the practic rendere more economica o v en nd fii'cihnt; the vanes are. r adi y and conveni n ly as embled in the ha d while the latter i's'm in inedin; true circu ar rm by the supporting clamps, and their accurate relation thereby then 'fixed, While all are exernal y ncorpora ed, as a un t ry m mbe wi hinjthe cn ing, annulus of core materialthat may be transported, stored or handled s desired hevanes are. held in su manr by he. annul s t at th sh nk cf e casting when cooling does not strain or dis place canes in the cast rim; since any strain movement is accommodated by and within the core-mater al ubstance I claim and desire to secure by Letters Patent:

1. The method of making turbine rotors, which consists in primarily arranging the perforated; metal band upon the peri" hery, of a pair of adjacent circularclamp-p ates, assembling therewith vanes, having; reduced shanks and transverse shoulders, said vanes disposed in their requiredorder withtheir reduced shanks inserted? through said perforated metal band and; projecting inward between said clamp-plates, rigidly securing the inwardly projecting shank portions of all the vanes between and by means of said clamp-plates, within; the circle of said band, placing said Clamp-plates with the assembled band and vanes coneentricallfy within an annular core-box and forming about the pe- 'riphery of the clamp-plate a complete unitary ring of core-material enveloping and embedding the said vanes and metal-band, removing the clamp plates and embedded parts from the core-box, releasing the clampplates from the inwardly projecting shanks, leaving the cylindrical annulus containing the vanes and band adapted for'placement within a suitably shaped nioldfor casting.

plied to and closed upon the shanks of the,

vanes within the circle of the band; form ing about said circle a completee'nvelopi'ng annulus of core-material baked'uoon the outward projecting vanes and externally em bracing said hand; then removing the clamp devices from the shanks, and casting a memher to embed said inward projecting shanks and to unite integrally with said vanes and band, and subsequently breaking out and removing the annulus of core-material.

3. In the art of making turbine rotors,

comprising a series of vanes assembled with a smooth-faced flexible band having spaced apertures through which the shanks of the vanes are inwardly projected; the imethod which consists in primarily supporting the band upon the cylindrical periphery face of adj acently disposed clamp-plates, assembling the series of vanes therein with their shanks projecting inward between said clampplates; temporarlly confining the shanks and vanes rigidly in their assembled relation by,

closure of said clamp-plates, forminq around the exterior face of said band and envelopmg the outward radially pro ecting ends of the entire series or" clamped vanes, a flat cylindrical encasing annulus of core-material compacted and baked thereon; then releasing the shank-confining means, andbed said projecting shanks, and to unite integrally with said band.

4:. In the method of making turbine.

rotors,,inc1uding a continuous band-strip of thin metal approximately corresponding to; the desired width of the rotor-wheelrim, and having a spaced series of perforations therethrough, the improvement which consists in arranging said band about the exteri'or circumferential face of aseparable circular form, assembling therewith, liii their properly positioned relation, a series of vanes having reduced shanks with said shanks inwardly projected through said subsequently casting awheel member to emband, then encasing the outward projecting part of thevanes, adjacent the outer face of the band, with plastic core-material to form a complete surrounding core annulus, treating said core :annulus to render the same sufficiently rigid for handling as a unitary ring, and for maintaining theassembledparts in positively fixed relation therein after the separable circular form has been removed from the interior of the'band.

. 5. The herein described method in making a'turbine rotor, which consists'in. temporarily supporting a series of turbine vanes having their shanks inwardly projected through apertures. in; a thin-circular band,

by a circular separable clamping means, the circumferential face of whichliorms a support for said band, disposing saidclamping means within a cylindricalreceptacle'and compacting therein about, thevanes and. band an encasing-body of plastic core-material forming a complete annulus, drying and hardening said coreematerial to solid conditionupon the vanes, andthen "releasing a the clampingmeans therefrom thereby af-t fording a unitary annular vane-retaining member adapted for convenienthandling and for ready insertion in] the matrix of, a wheel-casting'mold. j. v a 7 Witness my hand this QOtlr 'dayof ,Febr'u'- ary,1918. a v, -AXEL wyoa'jniisong 

